1. Field of the Invention
The present invention relates to a method and an apparatus for providing control information of a multi-input-multi-output (referred to as “MIMO” hereinafter) system, and more particularly, to a method capable of acquiring control information of another user executing cooperative transmitting and receiving functions of an MIMO system.
2. Description of the Related Art
According to a Long Term Evolution (LTE) specification, a multiuser MIMO (referred to as “MU-MIMO” hereinafter) technology is used as an essential approach to enlarge a downlink throughput of user equipments of a cell-edge.
A procoding vector is used to remove interference between MU-MIMO user equipments using the same frequency in an MU-MIMO system based on a code book storing a Precoding Matrix Index (PMI).
In a 3GPP LTE, a control channel called a Physical Downlink Control Channel (PDCCH) including loaded control information through downlink control information (DCI) is transmitted. At this time, a base station selects a precoding vector from a code book and transmits the selected precoding vector to a user equipment through the DCI of a PDCCH.
However, in a conventional DCI, when there are more user equipments than two performing cooperative communication using the same frequency, one of the user equipments can know its precoding vector but cannot know precoding vectors of other user equipments.